In orthodontic/jaw orthopedic treatment, bands, braces and removable appliances as functional appliances etc. are used to align the teeth or to bring them at least approximately into a predeterminable tooth position. In order to assure the treatment result achieved for example with bands or (since after the removing of the bands or braces there is a high instability of occlusion at a simultaneous optimum reactivity of the periodontal structures) in order to carry out small position corrections of the teeth (which cannot be carried out or can only be carried out with difficulties by the previously used apparati) after the bands are removed, precision adjustment apparati are inserted and are generally identified as "positioners".
Such positioners are formed individually either with the help of a so-called set-up-model (compare G. Schrems-Adam, H. Th. Schrems in "Fortschritte der Kieferorthopaedie" 37, 1976, Pages 473 to 478, translated English title: "Advances in the jaw orthopedics") or a set of few positioners of different size is premanufactured, which are dimensioned according to easily determinable parameters, namely either according to the total distance between two specific teeth of the jaw arch, which teeth lie symmetrically with respect to the jaw center, (German AS No. 16 16 125) or in consideration of the individual kinematics of the mandible according to the sum of the mesio-distal diameters of the teeth and according to the tooth arch form (German patent application No. P 32 32 550.9-35).
The tooth receiving cavities of the mentioned premanufactured positioners are thereby constructed such that they are very exactly adjusted to the outer contour of the teeth, so that the positioner snugly surrounds/rests on the teeth in the position which corresponds with the ideal set-up (ideal occlusion) position.
The tooth receiving cavities of individually manufactured positioners are constructed such that they are very exactly adjusted to the outer contour of the teeth, so that the positioner, after overcoming the incorrect tooth positions, finally snugly surrounds the teeth. The tooth receiving cavities of the mentioned premanufactured positioners are constructed such that they are very exactly adjusted to the outer contour of those teeth which were the basis for the original model during the creation of the ideal occlusion (set-up).
The outer entire contour of the teeth is, however, different from patient to patient, even with the same sum of the mesio-distal diameters of the teeth and the same tooth arch form.
Therefore, in practice when using the mentioned premanufactured positioners, there occurs the problem that, when the tooth receiving cavities of the positioner do not correspond with the outer contour of the teeth of the respective patient, an unintended position change of teeth relative to the desired ideal occlusion is caused. The unintended position change is greater the more diligently the patient wears his positioner. From this results but a high recidivism danger, namely the danger of falling back into a similar situation as existed prior to the start of the treatment.
If for example the chewing surface of a tooth due to a filling has no longer a natural form, then the positioner, the receiving cavity of which for this tooth corresponds with the form of the natural grooves and fissures of the chewing surface, applies a specially large pressure onto the chewing surface of said tooth which has the filling. The result is that this tooth is pressed into the alveolar process more strongly than the other teeth, which causes an unintended position change of this tooth. This position change has an effect on the adjacent teeth and can lead like a chain reaction to position changes of many other teeth and thus again destroy the desired tooth and jaw arch form.
The structure and operating principle of the conventional individually manufactured and premanufactured positioners thus is based on the fact that the desired position change of the still incorrectly positioned teeth is effected by the positioner material which due to its elasticity under chewing pressure rests snugly on the entire outer surface of the teeth. This treatment phase can be identified as the active positioner phase, because here tooth movements are still being constantly carried out by the positioner.
If during the course of weeks or months, by correct wearing of the positioner, the teeth have been forced into their ideal position (set-up position), then the positioner is supposed to maintain this achieved ideal position. This treatment phase can be called the passive positioner phase, because tooth movements are no longer effected by the wearing of the positioner.
However, the experience shows that usually when mandibular kinematics are not considered when creating the set-up (which is common usage because of the high time and technical input required), the passive position of the maxillary and mandibular teeth, in which position they are held by the positioner, is not a functional one.
If the patient removes the positioner from the mouth, the maxillary and mandibular teeth meet differently than they meet in the positioner. Because of the complex relief structure of the occlusal surfaces, therefore premature contacts occur pointwise (merely at a point or points) on an individual tooth pair or on several tooth pairs during the first tooth contact in the hinge-axis closing-bit phase and thus individual teeth are overloaded and thus function-induced uncontrolled and uncontrollable deflections of the teeth occur, which finally lead to a chain reaction within the individual maxillary and mandibular tooth arches and between the tooth arches.
These tooth position changes take place within the tooth arches until, during the various functional and parafunctional loads, a load balance has occurred. In very many cases this load balance is not only achieved by tooth position changes which differ from the ideal treatment situation (set-up situation), but mainly by a compensatory misaligning (shifting) of the mandible relative to the maxilla. Thus one can differentiate between an alveolary compensation mechanism, which is caused by function, and a mandibulary (skeletal) compensation mechanism, which is also caused by function.
Furthermore experience shows that even in the case of maximum precision in treatment and in consideration of the individual kinematics of the mandible, only in exceptional cases is it possible to achieve the theoretically ideal set-up relationships in patients. Aside from technically caused errors in manufacture and material, it is mainly the impossibility of being able to sufficiently consider tissue behavior and tissue reaction that is responsible for this.
Therefore one can at most achieve a condition with the help of a precise orthodontic/jaw orthopedic therapy using the highest treatment precision, which condition comes close to the planned ideal condition. The last small position corrections of the teeth, which are necessary in order to assure optimum functioning and stable loading of all components, are carried out through natural compensation mechanisms, for example in the form of small tooth position changes or attritions by the organism itself. This individual adaptation operation can be identified as an individual settling-in.
Although it may be unjustified, this undesired position change of the teeth is often blamed on the patient by the treating person (dentist) for the reason that the patient is no longer wearing his treatment apparatus with the undesired position change as the necessary consequence.
Therefore, a method already has been disclosed which is supposed to secure a better retention. From German OS No. 26 08 797 it is known to apply a soft deformable material onto the positioner and to then insert the positioner into the mouth of the patient, after which the patient must close the teeth for a few minutes, until the applied material has become hard and has bonded with the base material of the positioner.
As stated above, however, such measures permit a prevention of unintended position changes of the teeth only so long as the apparatus is being worn subsequently. Just as in the case of the remaining known positioners, as soon as the apparatus of German OS No. 26 08 797 (which has been reset to function as a retention apparatus) is not worn and the teeth are "let go" on one another corresponding with functional conditions, the known consequence of undesired tooth position changes (recidiviation) occurs again, so that with this known apparatus is connected only an increased amount of work and a conserving effect, not, however, a long-time therapeutic effect.
Thus, it is also not possible with the positioner of German OS No. 26 08 797 to balance existing tooth form discrepancies between the patients' teeth and a premanufactured positioner, in order to achieve a better treatment effect of the premanufactured positioner. Here too is accomplished only a conserving effect on the just existing occlusion.
Mainly, however, the known positioner does not take any measures which concentrate on the respective terminal hinge axis position, or the ideal closing bite position, in which a maximum intercuspation in centric relation exists (centric relation occlusion). This has the result that, during biting into the known positioner, the condyles are strongly moved partly out of their fossae. After removing the known positioner there occurs therefore during intercuspation almost always a strong deflection of the condyles out of the fossae. This results in a strong mechanical influence on the joints and the neuromuscular system with mostly irreparable damage or consequent damage.
In other words, by using the conventional individually manufactured or premanufactured positioners, the tooth receiving cavities differ in form from the patients' tooth forms and/or have no function-coordinated set-up, and subsequent incorrect positions of the teeth thus always result, the latest after removal of the positioner.
The purpose of the invention is to produce a set of premanufactured positioners, which reliably maintains the result achieved by the orthodontic/jaw orthopedic treatment, without requiring additional work to be carried out on the premanufactured positioner.
This is achieved, under the present invention, by the tooth receiving cavities of the premanufactured positioner being constructed such that when the positioner is inserted, the pressure applied by the positioner onto the teeth is the greatest in the area of the occluding parts.
The basis of the present invention is thus the recognition that, with a specific tooth arch length and a specific tooth arch form, the positions of the cusp tips and incisal edges of the teeth (thus the positive occluding tooth parts) are practically identical in each patient, namely through the tooth arch length and the tooth arch form alone the position of these occluding tooth parts can be defined exactly. Variations of the teeth exist, however, in other anatomic respects and through specifically occurring tooth treatments.
In one anatomic respect, for example, when viewing the outer contour of the teeth in the gingival direction, the steepness of the side surfaces of the cusps and the side edges and the depth of the tooth grooves and fissures are different. During tooth treatment, for example, fillings must be considered.
Aside from the finding that, with a specific tooth arch length and tooth arch form, the position of the occluding parts of the teeth are defined exactly, the present invention furthermore is based on the recognition that, for holding of the teeth and for small position corrections, it is exclusively important that a force is applied on the occluding parts of the teeth. In contrast to the known positioners, in particular according to German AS No. 16 16 125 and German OS No. 26 08 797, it is thus not necessary that the positioner rest will all sides of its tooth receiving cavities fixedly against the teeth in order to securely hold the teeth.
This means that the nonoccluding parts of the teeth, which as mentioned can have different forms (with the same tooth arch length and tooth arch form) in anatomic respect and through specific tooth treatments, do not need to be exposed to any load, so that the tooth receiving cavities can be recessed or constructed very flexibly in the area thereof provided for receiving the nonoccluding parts of the teeth.
These recesses in the receiving cavities of the positioner in the area of the grooves and fissures of the teeth, also prevent, for example, the aforedescribed position change which occurs in the known positioner due to a tooth provided with a filling. It is also true that these recesses in the receiving cavities permit a greater contour of the teeth, in particular in labial and lingual direction.
Expressed differently, in the present invention use is made of the recognition that in a positioner, by building in of certain tolerances at points which are of subordinate importance or even unimportant for reciprocal stabilization of the tooth arches within themselves or between one another, no negative effects on the therapeutic result are to be expected.
The stabilization of the tooth arches with respect to one another is assured by the occluding parts, namely, the cusp tips and fissures (grooves) or enamel ridges. The occluding parts and here in particular the supporting cusp tips--in the maxilla these are the palatal cusp tips and in the mandible the buccal cusp tips--are for a predetermined tooth arch and jaw arch length almost constant to one another in their spacial position, independent of morphologic variations of the individual teeth. They furthermore have the advantage that dental therapy as fillings etc. have not as yet been carried out on them, especially at a child's age. They thus represent the best possible point of engagement for a premanufactured positioner. Also suited as a point of engagement are all parts which participate in occlusion, namely the incisal edges of the canines and incisors. However, they have the disadvantage of a high morphological variance and already have surface changes (abrasions) even at a child's age, which are caused by functional or parafunctional and malocclusion-caused overloads. They must then be timely compensated by grinding methods.
In case of the existence of tooth and jaw misalignments, the approach to the planned ideal condition (occlusion) has to occur thus with the help of known orthodontic/jaw orthopedic treatment devices.
It is now important to note that for the last fine corrections, which however are of the greatest importance for a stable function (treatment result), taking into consideration the individual kinematics of the mandible, so far satisfactory results have been achieved only with the known individually manufactured (custom made for each individual) positioners. Since the manufacture of such an individualized positioner however requires an almost unjustifiably large expense and with such an individualized positioner only a best possible approximation to the desired ideal situation can be achieved, the final definite adjustment must be done by the organism itself. A premanufactured positioner embodying the present invention is therefore disclosed hereafter, the operational effectiveness of which is based on the cusp tips (preferably the carrying cusp tips and the incisal edges of the teeth) as being the least changeable reference points of the set of teeth.
With this it is possible to achieve an optimum approximation to the ideal occlusion under varying morphologic conditions. The approximation effect with the inventive positioner is (according to experience to date) at least as great and often even better than with an individually manufactured positioner. The individual adaptation capability is stressed only to a minimum by the use of the inventive apparatus and is by no means overstressed. Unintended position changes of the teeth, which happen almost always when using premanufactured positioners because of the morphologic variance, are substantially and reliably prevented.
A further advantage is that the inventive positioner is able to make visible on time the causes (for example incorrect occlusal surface design due to fillings) of the creation of recidiviation, assuming that the correct position was chosen from the set using the known selection criteria (sum of the mesio-distal diameter of the teeth and tooth arch form of the patient).